Field of the Invention
The present invention relates to a center pipe for a plasma torch, a contact piece, an electrode, and a plasma torch.
Background Information
A plasma torch includes an electrode that acts as the originating point of an arc, and a nozzle disposed so as to cover the electrode. The electrode is attached to an electrode seat of a torch body. The nozzle is attached to the electrode via an insulation guide. The insulation guide positions the nozzle so that the nozzle is disposed concentrically with the electrode. The plasma torch causes a plasma arc to be generated between the electrode and a workpiece through an orifice of the nozzle.
Because the electrode is a consumable, the electrode is attached to the electrode seat of the torch body in a detachable manner. For example, the electrode as described in Japanese Laid-open Patent 2001-47247 has a tip end side cylindrical portion, a flange portion, and a base end side cylindrical portion. The flange portion has an outer diameter greater than that of the tip end side cylindrical portion and the base end side cylindrical portion. The electrode is attached to the electrode seat due to the base end side cylindrical portion being coupled to the inner surface of the electrode seat with a frictional resistance force. Alternatively, a female thread portion is formed on the electrode seat and a male thread portion is formed on the base end side cylindrical portion. The male thread portion of the base end side cylindrical part is screwed onto the female thread portion of the electrode seat, whereby the electrode is attached to the electrode seat.
While the electrode is attached to the electrode seat, the end surface in the axial direction of the flange portion is in contact with the tip end portion of the electrode seat. Moreover, the external circumferential surface of the base end side cylindrical portion is in contact with the internal circumferential surface of the electrode seat. That is, the external circumferential surface of the base end side cylindrical portion and the end surface in the axial direction of the flange portion of the electrode act as energization surfaces with the electrode seat. The electrode and the torch body are electrically connected through the above energization surfaces.